The present invention relates to an electromagnetically actuated valve useable in an anti-lock brake system for controlling brake fluid pressure in a vehicle.
Japanese Translation of PCT International Application No. 2000-512585 (corresponding to U.S. Pat. No. 6,092,781) discloses an electromagnetically actuated valve for hydraulic brake systems for motor vehicles. The electromagnetically actuated valve of this related art is a so-called normally open type pressure intensifying valve having the following structure. A housing has a pressure fluid path and a valve retaining bore in course of the pressure fluid path. The pressure fluid path has one end connected to a master cylinder and the other end connected to a wheel cylinder. A tubular valve casing made of metal is disposed within the valve retaining bore and has a radial passage radially extending through a circumferential wall thereof and communicated with the pressure fluid path. A valve seat is fixed into the valve casing and has an axial fluid passage communicated with the radial passage of the valve casing. A valve body is disposed within the valve casing and electromagnetically actuated to axially move and shift between an open position and a closed position. In the open position, the valve body is disengaged from the valve seat to allow fluid communication between the axial fluid passage of the valve seat and the radial passage of the valve casing, and in the closed position, the valve body is engaged with the valve seat to block the fluid communication therebetween.
Specifically, a cylinder is fixed to an upper end portion of the valve casing which acts as a stationary core. A plunger is slidably accommodated in the cylinder. A magnetic coil is disposed around the upper end portion of the valve casing. When the magnetic coil is de-energized, the valve body is kept in the open position to thereby allow the fluid communication between the axial fluid passage of the valve seat and the radial passage of the valve casing. When the magnetic coil is energized, the plunger is moved to urge the valve body to the closed position to thereby block the fluid communication between the axial fluid passage of the valve seat and the radial passage of the valve casing. Thus, a flow of the brake fluid flowing between the master cylinder and the wheel cylinder via the fluid path is controlled.